Abstract:

An electric toothbrush is provided, the electric toothbrush having a
housing, with a drive that is elastically mounted on the housing by means
of a spring device and can be moved in an oscillatory fashion in at least
one plane of motion, and with a transmission element that is connected to
the drive and serves for transmitting the driving motion to a brush head.

Claims:

1. A hand part of an electric toothbrush, the hand part comprising:a
housing,a drive that is elastically mounted on the housing by a spring
device and that can be moved with an oscillatory driving motion in at
least one plane of motion, andtransmission element that is connected to
the drive,wherein the spring device has different spring constants in two
different directions in the plane of motion of the drive such that the
oscillatory motion of the brush head has different amplitudes in the
these directions.

2. The hand part according to claim 1, wherein the spring device and the
driving frequency of the drive are adapted to one another in such a way
that the brush head carries out an elliptical driving motion.

3. The hand part according to claim 1, wherein the drive can be moved
along an elliptical motion path, the longitudinal axis of which is at
least five-times longer than the lateral axis, preferably more than
ten-times longer.

4. The hand part according to claim 1, wherein the drive comprises an
adjustment device configured to adjust.

5. The hand part according to claim 1, wherein the driving motion of the
drive has a lower amplitude in the direction of a poking motion than in a
lateral direction extending perpendicular thereto.

6. The hand part according to claim 1, wherein the spring device has two
principal axes with different spring constants, both of which lie in a
plane that extends transverse to the longitudinal axis of the toothbrush.

7. The hand part according to claim 1, wherein the spring device has a
greater spring constant along a first axis of motion, than along an
second axis of motion generally perpendicular to the first axis of
motion.

8. The hand part according to claim 1, wherein the spring device comprises
a labyrinth spring having with spring arms of different lengths.

9. The hand part according to claim 1, wherein the spring device comprises
a disk-shaped and/or plate-shaped member that extends in a plane that
lies substantially perpendicular to the longitudinal axis of the
toothbrush.

10. The hand part according to claim 1, wherein the spring device
comprises a mounting carrier clamped in the housing.

11. The hand part according to claim 1, wherein the spring device includes
an orientation coding such that the spring device can be installed in the
housing in a predetermined alignment.

12. The hand part according to claim 1, wherein the spring device includes
integral mounting sections for mounting the spring device on the drive
and/or the housing.

13. The hand part according to claim 1, wherein the spring device
comprises a sheet metal stamping.

14. The hand part according to claim 1, wherein the transmission element
and/or the drive is/are coupled to the housing in a multiaxially pivoting
fashion by a bearing.

15. The hand part according to claim 1, wherein the transmission element
is coupled to a through-opening section on the housing.

16. The hand part according to claim 14, wherein the spring device is
arranged on the side of the drive that lies opposite to the bearing.

17. The hand part according to claim 1, wherein the transmission element
is rigidly connected to the drive.

18. The hand part according to claim 1, wherein the drive features an
electric motor with an imbalance.

19. The hand part according to claim 1, wherein the spring device is
positively connected to the drive.

20. The hand part according to claim 1, wherein the drive is movably
suspended and is connected to rigid connections on the housing.

21. The hand part according to claim 20, wherein the drive includes
terminals, and the terminals of the drive are connected to the rigid
connections on the housing by flat metal strips.

22. An electric toothbrush, on which a brush head can be removably
mounted, the electric toothbrush comprising:a hand part comprising a
housing, a drive that is elastically mounted on the housing by a spring
device and can be moved with an oscillatory driving motion in at least
one plane of motion, and a transmission element that is connected to the
drive and configured to transmit the driving motion to the brush
head,wherein the spring device has different spring constants in two
different directions in the plane of motion of the drive such that the
oscillatory motion of the brush head has different amplitudes in the
these directions.

23. The electric toothbrush according to claim 22, wherein the spring
device has a greater spring constant along an axis of motion that extends
substantially parallel to a principal longitudinal direction of bristles
of the brush head relative to the spring constant transverse to this
principal longitudinal direction.

24. The hand part of claim 1 wherein the at least one plane of motion is
transverse to the longitudinal axis of the toothbrush.

26. The hand part of claim 14 wherein the bearing comprises an elastic
sleeve.

27. The hand part of claim 18 wherein the imbalance is provided by an
eccentrically mounted mass.

Description:

[0001]This application is the national stage of International Application
No. PCT/EP2006/011969 filed Dec. 13, 2006, which claims priority under 35
U.S.C. §119(a) to German Application No. 10 2006 004 146.1, filed
Jan. 27, 2006, the entire contents of which are hereby incorporated by
reference.

TECHNICAL FIELD

[0002]The present invention pertains to an electric toothbrush, that
includes a housing, a transmission element and a drive that is
elastically mounted on the housing by means of a spring device and can be
moved in an oscillatory fashion in at least one plane of motion. The
transmission element is connected to the drive and serves for
transmitting the motion of the drive to a brush head that can be attached
to the transmission element.

BACKGROUND

[0003]An electric toothbrush in which the entire driving motor vibrates
and these vibrations are transmitted to the brush head, is known from
U.S. Pat. No. 3,196,299. The driving motor drives an imbalance in the
form of an eccentrically supported mass and forms a vibratory drive
together with this imbalance. The driving motor is arranged in a chassis
that, in turn, is movably arranged on the housing of the toothbrush by
means of a spring. The vibrations of the drive are transmitted to a
transmission rod that is movably arranged in the housing and to which a
clip-on brush can be attached. The spring is clamped between
corresponding shoulders of the chassis and the housing and arranged at a
through-opening of the housing between the clip-on brush and the driving
motor. In this case, a relatively complicated screw mechanism is provided
for changing the spring prestress in order to thusly vary and adapt the
intensity of the vibrations or the motion amplitude of the drive to the
requirements of different users. Despite this adjustability, one
unsatisfactory aspect of such vibratory drives can be seen in that the
brush head carries out an excessively intense poking motion while the
wiping motion parallel to the tooth flanks is comparatively weak. In
addition to a limited efficiency, this can lead to the user experiencing
an unpleasant sensation while the toothbrush is used.

SUMMARY

[0004]In one aspect, the invention features a hand part of an electric
toothbrush, including a housing, a drive that is elastically mounted on
the housing by means of a spring device and can be oscillated in at least
one plane of motion, and a transmission element that is connected to the
drive and serves for transmitting the driving motion to a brush head. The
spring device has different spring constants in two different directions
in the aforementioned plane of motion of the drive such that the
oscillatory motion of the brush head has different amplitudes in the
these directions.

[0005]As a result, the direction of the generated driving motion of the
elastically suspended drive, and therefore the cleaning motion of the
brush head of the toothbrush is controlled, particularly such that said
driving motion has different amplitudes in different directions.
According to the invention, the spring device that serves for elastically
mounting the drive on the housing has different spring constants in two
directions in the plane of motion of the drive that preferably extend
perpendicular to one another, namely such that the driving motion of the
drive has different amplitudes in these directions. This makes it
possible to adjust the intensity of the vibrations in different cleaning
directions.

[0006]In some implementations, this makes it possible, in particular, to
reduce the intensity of the poking motions of the brush head, i.e.,
motions that are essentially directed parallel to the bristles of the
brush head, while the intensity of the wiping motions, i.e., motions of
the bristles that are directed parallel to the tooth flanks, can be
comparatively increased.

[0007]In some implementations, the spring constant of the spring device
may be greater along an axis of motion, along which the poking motions of
the brush head are carried out, than along an axis of motion, along which
the wiping motions of the brush head are carried out parallel to the
tooth flanks.

[0008]It is advantageous to adapt the spring device, particularly its
spring constants in the mutually perpendicular directions, and the
driving frequency of the drive, to one another in such a way that the
drive carries out an essentially elliptical driving motion or, if
applicable, an approximately oval driving motion or, in general terms, a
driving motion in the form of a flattened circle.

[0009]The drive can advantageously features adjusting means for adjusting
its driving frequency such that the driving frequency can be adapted to
the respective spring device and manufacturing tolerances in the drive
and/or the spring device, as well as deviations of the vibration
frequency resulting thereof, can be compensated.

[0010]In an additional implementation, the suspension, particularly its
spring device, and the drive itself are realized in such a way that the
amplitude of the driving motion in a first direction is preferably at
least five-times higher than the amplitude of the driving motion in a
second direction extending perpendicular thereto. If the drive carries
out the aforementioned elliptical vibratory or oscillatory motion, the
longitudinal axis of the motion ellipse may be at least five-times
longer, preferably more than ten-times longer, than the lateral axis of
the motion ellipse.

[0011]The spring device does not necessarily have to be aligned in
accordance with the oscillatory motion of the drive. In an additional
implementation, the spring device has two principal axes with different
spring constants, both of which lie in a plane that extends transverse to
the longitudinal axis of the toothbrush and may simultaneously form the
plane of motion of the drive.

[0012]According to one advantageous embodiment, the spring consists of a
labyrinth spring with spring arms that are designed differently from each
other in order to realize the different spring constants. It would be
possible, in particular, to provide spring arms of different lengths that
result in the dissimilarity of the spring constants.

[0013]The labyrinth spring may be realized, in particular, in an
approximately disk-shaped or plate-shaped fashion. The spring device may
be advantageously accommodated in the housing of the toothbrush
essentially perpendicular to the longitudinal axis of the toothbrush.

[0014]In order to simplify the assembly and to ensure the desired
alignment of the spring device and therefore the correct orientation of
the different spring constants in different directions, the spring device
may feature an orientation coding that makes it possible to install the
spring device in the housing in a predetermined alignment. The
orientation coding and/or the corresponding housing section may be
realized in such a way that the spring device can only be installed in
one predetermined alignment. This makes it possible to ensure, for
example, that the lower amplitude of the driving motion occurs in the
poking direction and the higher amplitude of the driving motion occurs in
the wiping direction. If so required, the orientation coding on the
spring device and/or the corresponding housing section, on which the
spring device can be mounted, may also allow several predetermined
installation positions in order to reverse the directions, in which the
higher amplitude and the lower amplitude occur, e.g., for different
applications. However, the preferred embodiment is the above-described
embodiment, in which the spring device can only be installed in one
predetermined alignment.

[0015]The spring device may feature, in particular, a mounting carrier
that preferably consists of a frame with the corresponding orientation
coding. The frame may suitably deviate from the rotational symmetry in
order to ensure that the spring is installed in the desired direction.

[0016]The aforementioned mounting carrier or, in particular, mounting
frame may be advantageously realized integrally with the aforementioned
labyrinth spring. According to one particularly advantageous embodiment,
the spring device may consist of a sheet metal stamping, wherein several
of these sheet metal stampings that are preferably realized congruently
may, if applicable, be stacked on top of one another in order to form a
spring assembly of sorts.

[0017]In an additional embodiment, the drive is not only suspended by
means of the aforementioned spring device, but also connected to the
housing at another coupling point. In a further embodiment, the
transmission element and/or the drive connected thereto may, in
particular, be coupled to the housing in a multiaxially pivoting fashion
by means of a bearing, preferably an elastic sleeve. In this case, the
bearing advantageously forms a rigid coupling on the housing similar to a
ball-and-socket joint such that the transmission element and/or the drive
connected thereto can carry out a tumbling motion similar to a
three-dimensional rocker on a conical orbit. It goes without saying that
the conical orbit does not have to have a circular cross section, but
advantageously can be in the form of an elliptical cone in the
above-described fashion.

[0018]The transmission element is coupled similar to a ball-and-socket
joint in the above-described fashion, in particular, at a center or
intermediate section, such that the transmission element describes a
double-conical orbit when it is set in motion by the drive. In this case,
the transmission element may extend through the housing in an opening on
the face of the hand part housing and extend out of the hand part on its
face, wherein the bearing is advantageously arranged in the region of the
through-opening. A brush head, particularly an exchangeable brush, can be
advantageously attached or coupled to the protruding section of the
transmission element. It is advantageous that the section of the
transmission element situated in the interior of the housing is rigidly
connected to the drive or a drive chassis accommodating the drive, on
which the aforementioned spring device engages.

[0019]In an additional embodiment, the spring device is arranged on the
side of the drive chassis that lies opposite to the bearing. It would
also be conceivable, in principle, to arrange the spring device between
said bearing and the drive. However, the spring device is preferably
arranged on the side of the drive that faces away from the transmission
element. Due to this measure, the spring device has a longer lever arm
referred to the bearing that respectively defines the conical or
double-conical motion path of the transmission element. Consequently, an
effective control of the driving motion can be realized with low spring
forces and a compact and lightweight spring device can be used.

[0020]In one advantageous embodiment, the drive consists of an electric
motor with an imbalance, e.g., in the form of an eccentrically arranged
mass. The imbalance is driven in a rotational fashion such that an
oscillating vibratory motion is achieved.

[0021]In order to realize a precise transmission of the spring forces to
the drive, the spring device can be positively and/or non-positively
connected to the drive or to a drive chassis accommodating the drive,
preferably in a non-wobbling fashion. In this case, the spring device
may, in particular, be riveted to the drive or its drive chassis,
respectively.

[0022]Due to the movable support of the entire drive and the corresponding
relative motion between the housing and the drive, the transmission means
of the energy supply and/or the control needs to allow the corresponding
motions. In this respect, it would be possible, in principle, to use
elastic lines or, if applicable, even sliding contacts. In some
implementations, the power supply of the drive and/or its control device
features rigid connecting points on the housing for connecting the
movably supported drive in the immediate vicinity of the bearing, by
means of which the transmission element and the drive are respectively
coupled to the housing. Almost no relative motions occur in the immediate
vicinity of this coupling point because this location quasi forms the
root of the double-conical motion path of the drive and the transmission
element connected thereto. The rigid connecting points of the power
supply and the control device on the housing consequently lie in a region
in which the motion amplitude of the drive train is very low.

[0023]In this respect, it is particularly advantageous to realize the
transmission means in the form of metal strips that connect the electric
terminals of the motor to the rigid connecting points on the housing. The
metal strips allow the aforementioned motions that essentially consist of
an angular offset at the aforementioned location. The drive may be
connected, in particular, to a printed circuit board that extends as far
as the vicinity of the bearing of the transmission element by means of
the aforementioned metal strips.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 shows a schematic side view of an advantageous embodiment of
an inventive electric toothbrush with a hand part and a clip-on brush
that can be attached thereto;

[0025]FIG. 2 shows a longitudinal section through the hand part of the
electric toothbrush according to FIG. 1 along the line B-B in FIG. 1;

[0026]FIG. 3 shows a longitudinal section through the hand part according
to the preceding figures along the line A-A in FIG. 2;

[0027]FIG. 4 shows a schematic front view of the brush head of the
toothbrush according to FIG. 1 that elucidates the motion path of the
brush head;

[0028]FIG. 5 shows a cross section through the hand part of the toothbrush
along the line F-F in FIG. 2, wherein this cross section shows the
suspension of the drive on the housing by means of a labyrinth spring,
and

[0029]FIG. 6 shows an enlarged top view of the spring device of the
suspension for the drive of the toothbrush according to the preceding
figures.

DETAILED DESCRIPTION

[0030]The electric toothbrush 1 illustrated in the figures comprises a
hand part 2, to which a brush head 3 can be attached, wherein the brush
head 3 in the embodiment shown comprises a brush tube 4, by means of
which the brush head 3 can be attached to the hand part 2.

[0031]The hand part 2 comprises an essentially tubular housing 5 that
accommodates an electric drive 6, as well as an energy source therefor,
particularly in the form of a battery or an accumulator, and may also
feature not-shown actuating and control elements.

[0032]According to FIGS. 2 and 3, the drive 6 is arranged in the front
section of the interior of the housing 5 of the hand part 2 and comprises
a transmission element 7 in the form of a rigid rod that protrudes from
the face of the housing 5 through a through-opening 8. The aforementioned
brush head 3 can be attached to the protruding section of the
transmission element 7 with its brush tube 4, wherein the transmission
element 7 and the brush head 3 feature suitable coupling means 9, for
example, in the form of clip-on means in order to connect the brush head
3 to the transmission element 7 in a torsionally and flexurally rigid
fashion.

[0033]In the region of the through-opening 8, the transmission element 7
is arranged in an elastic sleeve 10 seated in the aforementioned
through-opening 8. This sleeve 10 forms a pivot bearing similar to a
ball-and-socket joint and enables the transmission element 7 to carry out
three-dimensional vibratory motions relative to the housing 5, but
largely fixes the transmission element 7 axially. The sleeve 10 allows,
in particular, a double-conical motion path of the transmission element
7, the contacting cone points of which lie in the region of the sleeve
10.

[0034]The aforementioned transmission element 7 is rigidly connected to a
drive chassis 11, particularly in a flexurally rigid and preferably
inflexible fashion, such that the transmission element 7 carries out the
same motions as the drive chassis 11. The drive chassis carries the
actual drive 12 that consists of an electric motor 13 with an imbalance
14 in the form of a mass that is eccentrically arranged on the motor
shaft in the embodiment shown. The end of the drive chassis 11 that faces
away from the transmission element 7 is elastically suspended on the
housing 5 by means of a spring device 15. The spring device 15 preferably
consists of the labyrinth spring 16 that is illustrated in detail in FIG.
6.

[0035]In the embodiment shown, the spring 16 features a central mounting
section 17 that is coupled to an outer mounting section 20 by means of
spring arms 18 and 19 such that the central mounting section 17 can be
moved relative to the outer mounting section 20 by deforming the spring
arms 18 and 19. It is advantageous to rigidly mount the central mounting
section 17 on the drive 12, particularly the face of the drive chassis
11, namely in a positive and non-positive fashion. In this case, it would
be possible, in principle, to use a screw connection. However, it is
preferred to rivet the spring 16 to the drive chassis 11.

[0036]On the other side, the spring 16 is firmly clamped in the housing 5
with its outer mounting section 20. According to FIG. 6, the mounting
section 20 consists of a peripheral, essentially rectangular mounting
frame, on the opposite limbs 20a and 20b of which the aforementioned
spring arms 18 and 19 are fixed. According to FIGS. 2 and 3, the
aforementioned mounting frame 20 may be clamped between two sections of
the housing 5. For example, the mounting frame 20 may be clamped between
the abutting housing halves that are screwed to one another.

[0037]In this case, the mounting frame 20 advantageously comprises an
orientation coding 21 that cooperates with an orientation coding on the
housing 5 in such a way that the spring device 15 needs to be installed
in a predetermined alignment relative to the housing. Suitable
asymmetries may serve as orientation coding 21 in this case. In the
embodiment shown, the orientation coding 21 consists of a tab-shaped
projection on the mounting frame 20 and a corresponding recess in the
housing. The aforementioned tab-shaped or lug-shaped projection can
engage into the corresponding recess in the housing 5 such that the
alignment of the spring device 15, particularly the rotatory alignment
relative to the longitudinal axis 23 of the toothbrush, is defined.

[0038]The spring constant or spring stiffness of the spring device 15 is
realized differently along different axes. According to FIG. 6, the
spring arms 18 and 19 are respectively realized in an essentially
L-shaped fashion, wherein the two limbs of each spring arm 18 and 19 have
different lengths. In this case, the two spring arm sections 18a and 19a
that respectively extend essentially parallel to the X-axis are shorter
than the spring arm sections 18b and 19b that essentially extend parallel
to the Y-axis and therefore essentially perpendicular to the
aforementioned spring arm sections 18a and 19a. Consequently, the spring
16 shown in FIG. 6 has a lower spring stiffness in the direction of the
X-axis than in the direction of the Y-axis. Accordingly, the drive 6
coupled to the central mounting section 17 can be displaced easier and
farther in the direction of the X-axis (see FIG. 6) than in the direction
of the Y-axis. The difference between the spring constants along the
X-axis and the Y-axis of the spring 16 can basically be chosen
differently and is preferably adapted to the design and the driving
frequency of the drive 6. The spring stiffness of the spring 16 in the
direction of the Y-axis is advantageously at least 25% higher than the
spring stiffness in the X-direction.

[0039]With respect to the installation alignment of the spring device 15
that is defined by the orientation coding, it is advantageous that the
higher spring stiffness is realized in the direction that corresponds to
the poking direction or the principal direction 24 of the bristles of the
brush head 3 while the lower spring stiffness extends in the direction of
the X-axis and essentially perpendicular to the longitudinal axis 23 of
the toothbrush and the aforementioned principal direction 24 of the
bristles of the brush head 3. In order to elucidate this arrangement, the
alignment of the X- and Y-axes of the spring device 15 is illustrated in
FIG. 4 that shows a front view of the brush head 3.

[0040]Due to the thusly achieved suspension of the drive 6 that has a
different stiffness in different directions, the imbalance 14 (eccentric
mass) causes the drive to describe an essentially elliptical motion path
25 (see FIG. 4), the longitudinal axis of which is preferably about
ten-times to thirty-times longer than its lateral axis (see FIG. 4),
preferably about twenty-times longer. In this case, the highest amplitude
essentially occurs in the aforementioned X-direction while the lowest
amplitude of the oscillatory motion occurs in the aforementioned
Y-direction. Consequently, the bristle section on the brush head 3 only
carries out a slight poking motion in accordance with the oscillation in
the Y-direction, but a more significant wiping motion with a higher
amplitude parallel to the tooth flanks in accordance with the oscillation
in the X-direction. The elliptical motion path illustrated in FIG. 4 may
also assume a different angular position relative to the x- or y-axis,
but the poking motion in the y-direction should still be significantly
smaller than the wiping motion in the x-direction.

[0041]According to FIGS. 2 and 3, the vibratory motion of the drive 6
along the elliptical motion path illustrated in FIG. 4 is converted into
a tumbling motion of the transmission element 7 on a double cone, the
contacting cone points of which lie in the region of the bearing sleeve
10. It goes without saying that the rotating oscillatory motion of the
brush head 3 may be greater than the oscillatory motion of the drive 6 in
accordance with the lever ratios.

[0042]The driving frequency of the drive 6 is advantageously adapted to
the spring constants of the respective spring device 15 used in order to
compensate manufacturing tolerances of the spring and the drive in such a
way that the desired elliptical oscillatory motion is achieved. In order
to adjust the speed or driving frequency of the drive 6, the drive may be
controlled by means of an adjustable voltage stabilization circuit that
makes it possible to stabilize and adjust the supply voltage of the
electric motor 13 to the correct value.

[0043]The power supply and the control of the electric motor 13 are
advantageously not realized with conventional wires, but rather with
metal strips 27 that lead from the motor terminals to rigid connections
28 on the housing and advantageously lie in the region of the bearing
sleeve 10 and therefore in the region, in which the motion amplitude of
the transmission element 7 is very low, i.e., practically zero. It would
be possible, in particular, to provide a printed circuit board with the
rigid housing connections 28, to which the metal strips 27 are connected,
on the face of the housing 5, namely in the region of the through-opening
8 provided at this location.